The best mechanical head I have found not to deflect on quartering shots is the Rocky Mountain Snyper. I have used this head for 2 years now and have taken several deer with them. All have been complete pass throughs and ususally the entrance wound will be slightly larger than the exit wound. Great blood trails also. I don't know what your set up is, but this head does not require as much KE as some of the other mechanicals out there. IMO this is a great mechanical head that flies just like my field points.

http://www.rockymtbroadheads.com/01-snyper.html